1. Field of the Invention
This invention pertains to storage apparatus, and more particularly to apparatus for releaseably retaining computer tape cartridges.
2. Description of the Prior Art
Included in the ongoing improvements in the computer field are data storage tapes that occupy less space while containing as much data as prior tapes. For example, the IBM 3480 cartridge system tapes are considerably smaller than the prior cylindrical magnetic reel tapes.
The introduction of the IBM 3480 cartridge system tapes requires the design and development of containers for storing the cartridges. Desirable features of the containers include positive cartridge retention, easy cartridge removal, and good visibility of the stored cartridges. Further, the containers should be easily insertable into and removable from library storage equipment holding several rows of side-by-side containers.
A known cartridge system tape container comprises a pair of horizontal shelves divided into vertical compartments sized to accept the cartridges. At the rear of each compartment is a biasing member similar to a leaf spring that tends to push the cartridge forwardly out of the compartment. Each compartment includes a lower lip that retains the cartridge in the compartment against the leaf spring biasing force. A cartridge is removed by pushing the upper front corner backwardly. The leaf spring then tips the cartridge lower edge above the lip, where it is held by the leaf spring. While generally satisfactory, the numerous leaf springs in the container render it quite expensive to manufacture, and the leaf springs are subject to fatigue. Moreover, it is often difficult to remove a cartridge from a compartment of the described container using only one hand. The cartridge upper front corner must be pushed with care so that it is tipped forwardly in the compartment by the leaf spring far enough to be grasped on the top and bottom surfaces. Otherwise, placing a finger of each hand on the top and bottom cartridge surfaces is necessary to pull a cartridge from its compartment.
Another prior container employs a solid wall at the back of each compartment. A strip of friction material is adhered to the bottom front portion of each compartment, so that a stored cartridge rests on the strip. That design is quite unacceptable, because the cartridges are not positively retained within the compartments. They therefore easily fall out when the containers are moved by hand or machine. Paradoxically, the friction strip makes it difficult to intentionally manually remove a cartridge from the container.
A third prior container includes a back wall with a pin in each compartment. The pins are adapted to enter a cartridge tape throat or tape opening to hold the cartridge in place. That design is undesirable, because the pins may distort the cartridges. Moreover, the tapes may become contaminated with foreign material.
In addition to the shortcomings previously described, the prior tape containers suffer the handicap of being restricted to use with limited types of library storage racks. Conventional cartridge containers require mounting racks having flat shelves to accept the container top and bottom panels therebetween. In that arrangement, the containers are stored in close proximity to each other on four sides, with no clearance between them for manual grasping and removal from the storage racks. Consequently, to remove a prior container from the storage rack, it is necessary to first remove two cartridges from their compartments, insert a hand into each vacant compartment, pull the container from the rack, place the container in the desired location, and replace the two removed cartridges. Such a procedure is undesirably time consuming and cumbersome.
Typically, the older cylindrical magnetic tape reel storage racks do not have flat platforms that suit prior cartridge containers. As a result, the computer system owner is required to purchase new storage racks if he uses conventional containers when converting to the new 3480 tape cartridges.
Thus, a need exists for an inexpensive tape cartridge storage system that positively retains the cartridges in containers that are compatible with pre-existing tape reel racks.